Images

Item can be crafted

Following familiars can be tamed with item

Where you can get Rodesh Mark

As you probably have already guessed you can either craft it, get it as a drop from World Bosses(such as 52lvl SandStorm, his location shown on picture here), get as a daily reward or achievement reward from random heroic familiar mark box or buy at the Market from other players.

Where you can get Rodesh Mark Recipe

You can get recipe for Rodesh Mark as a drop from bosses in the Fractura such as:
Fractura Commander Bil'rahn,
Captain Shu'khan,
Raid Captain Yeritz.